Teardrop Procedure Turn as a Course Reversal
Joined: Jan 2008
Posts: 2,173
Likes: 51
From: Blighty (Nth. Downs)
Comparisons with KLAX
Hi aterpster,
What date is your chart? I'm now kicking myself for choosing KLAX as an example yesterday. The Jeppesen charts I found on the 'net had the note I described, but not the threshold DME marked on the profile (although you can fairly easily calculate it from the distance-to-go marks). I didn't note the dates. 24 hrs on, the only Jeppesens I can find (using the same search engine) are dated April 2002 (yes!) and are as you describe. Seems odd, but I guess the Jeppesen format is constantly evolving.
The plot thickens. In 2002, it appears that all the ILS-DMEs at KLAX were sited with the LLZ antennae of the ILS being used. However, a series of FAA charts dated 2011 show that the ILS-DMEs were by then all sited at the western LLZ antennae. So, for example, the ILS-DME for Rwy 06L is sited at or near the LLZ antenna for Rwy 24R (and shares the same frequency of Ch 22). That means you fly over it (DME=0) about 0.5 nm before the threshold. Not ideal, IMHO, but that may be how it is right now (probably a money-saving exercise).
Quote:
"In any case once I pass the P-FAF (JETSA) I am not concerned about DME readings with a full ILS, including that threshold DME reading. That is for the GS-out fellow. My missed approach point is predicated on DA. The next DME fix I might be concerned about after DA is:
RAFFS D15.1 LAX"
You are correct to say that, having intercepted the GS and checked your altimeter at JETSA (D8.2), there is no further requirement to monitor the DME, or your distance from touchdown. But I guess you agree it's always useful to monitor your track miles to go, for a variety of reasons, not the least of which are spacial orientation and energy management, particularly in a heavy jet. For example, you may be on a base leg; either self-positioning visually, or under radar. The easiest way to do that is with a DME like the one at Aruba, which is sited close to the touchdown point. But, otherwise, you need to know what the DME will read at touchdown.
What date is your chart? I'm now kicking myself for choosing KLAX as an example yesterday. The Jeppesen charts I found on the 'net had the note I described, but not the threshold DME marked on the profile (although you can fairly easily calculate it from the distance-to-go marks). I didn't note the dates. 24 hrs on, the only Jeppesens I can find (using the same search engine) are dated April 2002 (yes!) and are as you describe. Seems odd, but I guess the Jeppesen format is constantly evolving.
The plot thickens. In 2002, it appears that all the ILS-DMEs at KLAX were sited with the LLZ antennae of the ILS being used. However, a series of FAA charts dated 2011 show that the ILS-DMEs were by then all sited at the western LLZ antennae. So, for example, the ILS-DME for Rwy 06L is sited at or near the LLZ antenna for Rwy 24R (and shares the same frequency of Ch 22). That means you fly over it (DME=0) about 0.5 nm before the threshold. Not ideal, IMHO, but that may be how it is right now (probably a money-saving exercise).
Quote:
"In any case once I pass the P-FAF (JETSA) I am not concerned about DME readings with a full ILS, including that threshold DME reading. That is for the GS-out fellow. My missed approach point is predicated on DA. The next DME fix I might be concerned about after DA is:
RAFFS D15.1 LAX"
You are correct to say that, having intercepted the GS and checked your altimeter at JETSA (D8.2), there is no further requirement to monitor the DME, or your distance from touchdown. But I guess you agree it's always useful to monitor your track miles to go, for a variety of reasons, not the least of which are spacial orientation and energy management, particularly in a heavy jet. For example, you may be on a base leg; either self-positioning visually, or under radar. The easiest way to do that is with a DME like the one at Aruba, which is sited close to the touchdown point. But, otherwise, you need to know what the DME will read at touchdown.
Guest
Joined: Apr 2009
Posts: 3,336
Likes: 0
From: On the Beach
Chris Scott:
KLAX 24R, dated July 12, 2012. It is current because the folks for whom I do most of my consulting work mantain a subscription for the 50 states. LAX is an airport that I am very familar with. It was my home base for most of my 27 years as an airline pilot.
I don't ever recall DME info being charted other than it is today (once the ILS DMEs were added, that is), but I tend not to recall such minuta.
My memory is not solid on the location of the DMES either. We just used whatever was charted at the time. I do have FAA source for IAPs going back to 1998. I will look up old source for 24R and 6L later on.
Because of my airline's route structure we usually arrived from the east. Visuals were never done arriving from the east. But, we also flew down from KSFO a fair amount, which brings you over SMO VOR for a visual weather permitting. At that stage of the flight we were constrained by speed assignments and turning onto the correct ILS for reference and regulatory compliance. I certainly didn't use DME for the north visual because it was, and is, predicated on the Los Angeles Coliseum (CVFP, Stadium Visual, Jepp 19-1).
As to IMCs, once passing the P-FAF, our concern was flying the ILS to DA without including the DME in our scan. We were highly standardized for all ILS IAPs on our system, many of which did not have DME in those days.
What date is your chart? I'm now kicking myself for choosing KLAX as an example yesterday. The Jeppesen charts I found on the 'net had the note I described, but not the threshold DME marked on the profile (although you can fairly easily calculate it from the distance-to-go marks). I didn't note the dates. 24 hrs on, the only Jeppesens I can find (using the same search engine) are dated April 2002 (yes!) and are as you describe. Seems odd, but I guess the Jeppesen format is constantly evolving.
I don't ever recall DME info being charted other than it is today (once the ILS DMEs were added, that is), but I tend not to recall such minuta.
The plot thickens. In 2002, it appears that all the ILS-DMEs at KLAX were sited with the LLZ antennae of the ILS being used. However, a series of FAA charts dated 2011 show that the ILS-DMEs were by then all sited at the western LLZ antennae. So, for example, the ILS-DME for Rwy 06L is sited at or near the LLZ antenna for Rwy 24R (and shares the same frequency of Ch 22). That means you fly over it (DME=0) about 0.5 nm before the threshold. Not ideal, IMHO, but that may be how it is right now (probably a money-saving exercise).
"In any case once I pass the P-FAF (JETSA) I am not concerned about DME readings with a full ILS, including that threshold DME reading. That is for the GS-out fellow. My missed approach point is predicated on DA. The next DME fix I might be concerned about after DA is:
RAFFS D15.1 LAX"
You are correct to say that, having intercepted the GS and checked your altimeter at JETSA (D8.2), there is no further requirement to monitor the DME, or your distance from touchdown. But I guess you agree it's always useful to monitor your track miles to go, for a variety of reasons, not the least of which are spacial orientation and energy management, particularly in a heavy jet. For example, you may be on a base leg; either self-positioning visually, or under radar. The easiest way to do that is with a DME like the one at Aruba, which is sited close to the touchdown point. But, otherwise, you need to know what the DME will read at touchdown.
RAFFS D15.1 LAX"
You are correct to say that, having intercepted the GS and checked your altimeter at JETSA (D8.2), there is no further requirement to monitor the DME, or your distance from touchdown. But I guess you agree it's always useful to monitor your track miles to go, for a variety of reasons, not the least of which are spacial orientation and energy management, particularly in a heavy jet. For example, you may be on a base leg; either self-positioning visually, or under radar. The easiest way to do that is with a DME like the one at Aruba, which is sited close to the touchdown point. But, otherwise, you need to know what the DME will read at touchdown.
As to IMCs, once passing the P-FAF, our concern was flying the ILS to DA without including the DME in our scan. We were highly standardized for all ILS IAPs on our system, many of which did not have DME in those days.
Joined: Jan 2008
Posts: 2,173
Likes: 51
From: Blighty (Nth. Downs)
Aterpster,
Thanks for that. I also grew up in a world where DMEs were not available for ILS procedures, and GS verification was predicated on L-NDBs (locator-NDBs) and/or 75MHz fan-markers. In the case of an initial-approach tear-drop like Aruba, the moment to start the base turn was decided by timing, on the basis of the forecast wind... Since then, you may agree, we all became thoroughly "spoilt" by DMEs and FMS displays. (However, not all our readers will be aware that the compelling nature of an FMS NAV display can get you into a lot of trouble if you fail to recognise map shift when present.)
If I'd known you were a veteran into KLAX, and with access to current charts, I could have saved myself a lot of trouble! Anyway, I've enjoyed trading insults.
Thanks for that. I also grew up in a world where DMEs were not available for ILS procedures, and GS verification was predicated on L-NDBs (locator-NDBs) and/or 75MHz fan-markers. In the case of an initial-approach tear-drop like Aruba, the moment to start the base turn was decided by timing, on the basis of the forecast wind... Since then, you may agree, we all became thoroughly "spoilt" by DMEs and FMS displays. (However, not all our readers will be aware that the compelling nature of an FMS NAV display can get you into a lot of trouble if you fail to recognise map shift when present.)
If I'd known you were a veteran into KLAX, and with access to current charts, I could have saved myself a lot of trouble! Anyway, I've enjoyed trading insults.
Guest
Joined: Apr 2009
Posts: 3,336
Likes: 0
From: On the Beach
If I'd known you were a veteran into KLAX, and with access to current charts, I could have saved myself a lot of trouble! Anyway, I've enjoyed trading insults. 
1. The current 24R/6L Jepp charts.
2. The source documents for April, 2002.
3. The current FAA charts.
Index of /LAX
As you can see from Item 2 indeed there were two separate DME transmitters for each runway end then. They are at the far end of each runway. (The FAA never has biased DME transmitters, so these had to be two separate transmitters.)
Joined: Jan 2008
Posts: 2,173
Likes: 51
From: Blighty (Nth. Downs)
Comparison of ILS DME at Aruba with KLAX (Los Angeles) - continued
aterpster,
Many thanks for the links to the current Jeppesen and FAA charts for KLAX ILS Rwy 06L and ILS Rwy 24R, and FAA documentation for the procedures prior to the resiting of the DME station used for the ILS 06L.
For others, and in confirmation of my previous post, the latter show that the old DME for Rwy 06L was withdrawn, and the ILS 06L now uses the same DME as the ILS 24R. This means that, on the ILS 06L, the DME reading at the threshold changed from 2.1 (falling) to 0.5 (rising). That is because, whereas the old siting was beyond the far end of the runway (near the localiser antenna), the new one is 0.5 nm before the threshold (near the 24R localiser antenna). So the DME reads zero at a point 0.5 nm before the threshold, reads 0.5 at the threshold, and about 0.7 at the touchdown point.
The ILS 24R is unaffected, because the DME siting has not changed. The reading remains about 2.0 at the threshold, and about 1.9 at the touchdown point. The change of DME siting seems to have been repeated on the three other reciprocal runways at KLAX, halving the number of DMEs needed.
For those who haven't been following this discussion, the Aruba DME station is sited to the side of the runway, close to the touchdown point and the GS antenna. It has only one approach to serve: ILS Rwy 11. It reads 0.2 at the thresold and zero at the touchdown point.
Quote:
"(The FAA never has biased DME transmitters, so these had to be two separate transmitters.)"
Yes, the biased systems are a device in some other countries to enable one, airfield-sited DME not only to serve two reciprocal runways, but also to read zero at the touchdown points (see my post above). The DME is normally sited equidistant from the two thresholds, so that the bias does not need to be changed when the duty runway is switched. However, it can lead to a surprise, because the DME may be reading a negative value as you vacate the runway, or (briefly) during a missed approach.
Many thanks for the links to the current Jeppesen and FAA charts for KLAX ILS Rwy 06L and ILS Rwy 24R, and FAA documentation for the procedures prior to the resiting of the DME station used for the ILS 06L.
For others, and in confirmation of my previous post, the latter show that the old DME for Rwy 06L was withdrawn, and the ILS 06L now uses the same DME as the ILS 24R. This means that, on the ILS 06L, the DME reading at the threshold changed from 2.1 (falling) to 0.5 (rising). That is because, whereas the old siting was beyond the far end of the runway (near the localiser antenna), the new one is 0.5 nm before the threshold (near the 24R localiser antenna). So the DME reads zero at a point 0.5 nm before the threshold, reads 0.5 at the threshold, and about 0.7 at the touchdown point.
The ILS 24R is unaffected, because the DME siting has not changed. The reading remains about 2.0 at the threshold, and about 1.9 at the touchdown point. The change of DME siting seems to have been repeated on the three other reciprocal runways at KLAX, halving the number of DMEs needed.
For those who haven't been following this discussion, the Aruba DME station is sited to the side of the runway, close to the touchdown point and the GS antenna. It has only one approach to serve: ILS Rwy 11. It reads 0.2 at the thresold and zero at the touchdown point.
Quote:
"(The FAA never has biased DME transmitters, so these had to be two separate transmitters.)"
Yes, the biased systems are a device in some other countries to enable one, airfield-sited DME not only to serve two reciprocal runways, but also to read zero at the touchdown points (see my post above). The DME is normally sited equidistant from the two thresholds, so that the bias does not need to be changed when the duty runway is switched. However, it can lead to a surprise, because the DME may be reading a negative value as you vacate the runway, or (briefly) during a missed approach.
Guest
Joined: Apr 2009
Posts: 3,336
Likes: 0
From: On the Beach
Chris Scott:
That FAA chart for the current ILS 24R is quite a mess. The saving grace is that it is unlikely that anyone who flies into LAX uses FAA charts.
Many thanks for the links to the current Jeppesen and FAA charts for KLAX ILS Rwy 06L and ILS Rwy 24R, and FAA documentation for the procedures prior to the resiting of the DME station used for the ILS 06L.
Idaho, but it ain't so in ICAO Doc 8168 land
